The following post was written by ff254 over on meta.academia. I can't better it, so here it is in its entirety (except I've changed the site title):
In 2014, Stack Exchange will continue its tradition of the "Winter Bash". Winter Bash is an annual event that can run on any Stack Exchange site that chooses to participate. Users earn “hats” for their gravatars by completing certain tasks (analogous to badges). Certain actions trigger the user receiving a hat, which their gravatar can “wear”. We track everyone’s progress earning hats in a leaderboard that looks something like this:
Stack Exchange sees Winter Bash as a a fun and lighthearted way to celebrate the amazing people who make the sites awesome, as the year draws to a close. Three things to note:
- Any user can opt out (clicking an option in your profile means you won't see any hat at all).
- Apart from the wearing of hats by avatars, the site is otherwise unaffected (there is no “holiday” theme of the site's design, for example)
- After the event ends, the hats disappear without a trace.
You can see FAQs from last year's promotion here.
This being said, we (as a community) also have to choice to opt out entirely and have the Winter Bash completely disabled on Sustainability Stack Exchange (no hats for anyone). In 2013, we chose to participate.
To decide whether we will participate in the Winter Bash 2014 Edition, I've created a “poll” below this post, with two comments. Upvote one of the comments according to your preference. If you want to discuss further, leave an answer or comments to other answers.